Generally, a vehicle is provided with a parking brake system preventing arbitrary movement of the vehicle and allowing the vehicle to be firmly fixed to the ground at the time and location of parking the vehicle, and the parking brake system is operated by a parking switch assembly installed in the vehicle.
Meanwhile, a hybrid bus may include two air parking switches 1 and 2, as illustrated in FIG. 1, and when a parking operation is performed in the hybrid bus, required torques (a motor torque and an engine torque) are made to become 0, such that power is not generated.
An air parking switch is connected to a hybrid control unit (HCU) controlling an ISG (Idle Stop and Go) and a torque, a transmission control unit (TCU) for learning and gear engagement, and a cluster of a parking operation.
However, a parking brake of the hybrid bus according to the related art may be recognized through the air parking switch mounted on an air line. However, when a breakdown occurs in the air parking switch or foreign materials are introduced into the air line or moisture is introduced into wiring, such that a short-circuit is generated, the HCU connected to the air parking switch registers that parking is completed in a situation in which the parking is not actually completed to make the motor torque and the engine torque 0 through a parking mode, such that a vehicle stop is maintained even at the time of desired acceleration, thereby making driving impossible.